The present invention relates to a vehicle with electric motors which has electric motors functioning at least as drive sources.
Among related vehicles with electric motors, there is a hybrid four-wheel drive vehicle, for example, which installs an engine and electric motors (hereinafter, referred to as motors). In this hybrid four-wheel drive vehicle, the engine and the electric motor are installed, for example, at a front end thereof so that front wheels are driven using the engine and the motor so installed. In addition, the other motors are installed at a rear end of the vehicle so that rear wheels are driven using these motors.
In the related hybrid four-wheel drive vehicle of this type, the front motor is allowed to function as a generator when braking. Namely, when braking, kinetic energy is converted into electric energy (regenerative energy), which can be stored (charged) in a high voltage battery which is provided separately from a low voltage battery for driving auxiliary equipment. On the other hand, when accelerating the vehicle, the stored electric energy is taken out (discharged) from the high voltage battery for use for acceleration. Due to this, with the hybrid four-wheel drive vehicle, effective use of energy can be enjoyed largely when compared with a related normal four-wheel drive vehicle which is driven only by an engine.
Incidentally, in this related art, since the rear motors are disposed by making use of a space between the left and right drive wheels, a space for disposing a fuel tank (a gasoline tank) is reduced by a space occupied by the motors, leading to a problem that disposing an enlarged fuel tank is difficult.
On the other hand, as the other related art, there is known an in-wheel motor type vehicle (for example, refer to Patent literature Nos. 1 and 2) in which a motor is placed in a drive wheel so as to rotate and drive the drive wheel.
[Patent Literature No. 1]
JP-A-2000-16040 (page 3, FIG. 1) 
[Patent Literature No. 2]
JP-A-2000-343920 (page 3, FIG. 2) 
Then, a related in-wheel motor type vehicle of this type will be described by reference to FIGS. 7 to 9. FIG. 7 is a schematic view illustrating the overall structure of the vehicle, and FIG. 8 is a partially enlarged view illustrating a suspension, a motor and the like of the vehicle. Additionally, FIG. 9 is an explanatory view illustrating the movement of the drive wheel and the motor.
Drive wheels 103 are provided at the front and rear of a vehicle body 102 (refer to FIG. 8) of an in-wheel motor type vehicle (hereinafter, referred to as a vehicle) 101 shown in FIG. 7 via suspensions 108, which will be described later on. In addition, a fuel cell 104 and a fuel tank 105 are installed at the front and rear of the vehicle 101, respectively. Then, the fuel cell generates electricity using hydrogen supplied from the fuel tank 105, and electric energy so generated is stored in a battery 106. In addition, the battery 106 is designed to drive motors 113, which will be described later, via a PDU (Power Drive Unit) 107.
In FIG. 8, the suspension 108 is provided between the vehicle body 102 and the drive wheel 103. Then, this suspension 108 includes, roughly speaking, an upper arm 109 and a lower arm 110 which are mounted between the vehicle body 102 and the drive wheel 103 in such a manner as to be vertically spaced away from each other and to oscillate, and a shock absorber 112 attached to a position along the length of the lower arm 110 via a connecting portion 111 (a connecting portion on the vehicle body 102 side is not shown). Additionally, the motor 113 is installed in a wheel 103A of the drive wheel 103, and the motor 113 includes a stator 113A and a rotor 113B.
In the related vehicle 101 constructed as is described above, the four drive wheels 103 are rotated to be driven by activating the motors 113 in the wheels 113A of the drive wheels through feeding from the battery 106. In addition, when vibrations and shocks are applied to the drive wheel 103 from the road surface while running, impacts from those vibrations and shocks are reduced by the shock absorber 112 while the drive wheel 103 is oscillating vertically relative to the vehicle body 102 via the upper arm 109 and the lower arm 110.
Additionally, in the related art like this, the motor 113 is designed to be accommodated in the wheel 103A of the drive wheel 103, when compared with the aforesaid hybrid four-wheel drive vehicle, wide spaces for mounting the fuel cell 104 and the fuel tank 105 can be secured between the left and right drive wheels 103, 103, as shown in FIG. 7, thereby making it possible to attempt to facilitate the enlargement of the fuel cell 104 and the fuel tank 105.
Incidentally, in the vehicle 101 according to the other related art, the motor 113 is designed to be accommodated in the wheel 103A of the drive wheel 103. Namely, in this related art, a construction is adopted in which, as shown in FIG. 8, both the drive wheel 103 and the motor 113 are disposed on one side which constitutes an opposite side to the vehicle body 102 across the shock absorber 112 (the connecting portion 111) (refer to FIG. 9).
Due to this, when shocks and/or vibrations are applied to the vehicle 101, the drive wheel 103 and the motor 113 move vertically together around the connecting point 111 as a fulcrum, as shown in FIG. 9, and as this occurs, inertia energy (moment) resulting from the drive wheel 103 and the motor 113 constitutes a large load which then acts on the shock absorber 112.
As a result, the weight of a lower side of the suspension 103 or a so-called unsprung weight is increased, and the follow-up properties relative to irregularities on the road surface at the time of running are deteriorated, leading to a problem that the riding comfort is deteriorated.